It is often desirable to deposit a thick foam of insectide, herbicides and other materials. Foams are useful for several reasons. First of all, foams are economically better than liquid sprays. A foam consumes substantially less material than a liquid spray. As such, foams also improve the environmental impact of using insecticide and herbicides since less of those hazardous materials are used to achieve equal or better results. Where a given insecticide application might require gallons of liquid, a corresponding foaming application may require only ounces.
Foaming devices known in the art are frequently of complex design and consequently expensive to manufacture. Typically they require both an air compressor and a liquid pump, the output from the compressor and the pump being directed to a turbulence chamber where they are mixed with a liquid in order to produce foam.
U.S. Pat. No. 2,653,848 to Lee discloses a device for attachment to an existing container, for example, a conventional tin-plate container or a glass gallon jug. A solution in the container is agitated to form bubbles, and the resulting foam is dispensed from the device. Included in the device is a pump with a tubular body that has a screw thread for attachment to the container. The body of the pump is divided by an air-tight partition into two chambers, the upper chamber containing a hand pump piston, the lower being a chamber for condensing the foam. The upper chamber is connected to an air injector tube that extends below the level of the liquid in the container, and the lower chamber is connected by a nipple to a foamer hose that has a length that is about 65 times its base diameter.
U.S. Pat. No. 3,970,219 to Spitzer et al. discloses an aerosol container for foaming and delivering an aerosol. It has a pressurized container with a valve for opening and closing a delivery port. The container is divided into two compartments by a porous bubbler that provides the only fluid communication between the two compartments. The first compartment contains foam, which is dispensed through the port when the valve is opened to the atmosphere. The second compartment contains compressed propellant gas, for example, nitrogen, air, a hydrocarbon, or a fluorocarbon.
U.S. Pat. No. 4,531,659 to Wright and U.S. Pat. No. 5,037,006 to Kock both disclose squeeze bottle devices that include a container for a foamable liquid. Foam is dispensed from an outlet of the device when the container is in an inverted position.
U.S. Pat. Nos. 3,831,850 to Hunter, 4,875,781 to Raska, and 4,880,312 to Carlson a disclose mixing containers from which paint can be dispensed. Each has an interior vane or baffle for agitating the paint mixture. U.S. Pat. No. 5,314,096 to Fesl et al. shows mixing vanes mounted on a hand pump. Operating the pump causes the vanes to turn.
A need remains for a hand-held foaming apparatus that is readily manufactured and easily operated. The present invention meets this need.